Figure 1.
Microscopic morphology of the GW-532 human Hodgkin's lymphoma and xenografts derived by serial transplantation in the hamster cheek pouch.
(A) Sections of the original axillary mass showed involvement by a lymphohistiocytic infiltrate composed of small lymphocytes, histiocytes, and plasma cells. Rare atypical mononuclear cells with features of Hodgkin cells were identified (arrow, Hodgkin-Reed-Sternberg cell). Immunohistochemical labeling of the original human tumor identified cells of (B) B/monocyte-cell origin (CD74+), and (C) macrophages (CD68+). A Hodgkin cell (arrow) is negative for CD68. Uniform morphological characteristics of the xenograft tumors from generations 2 (D), 25 (E), and 115 (F) were constant over time. The individual cells are large with vesicular chromatin and prominent central nucleoli. Occasional cells with binucleate or bilobed nuclei are present. Scale bar within image F corresponds to 100 µm for all images.
Figure 2.
Microscopic morphology of GW-584 human mediastinal lymphoma and xenografts derived by serial transplantation in the hamster cheek pouch.
(A) Sections of the original tumor showed effacement of the lymph node architecture. There was an extensive non-necrotizing granulomatous reaction with rare atypical mononuclear cells (inset) consistent with Hodgkin cells. (B) Immunohistochemical labeling of the original human tumor identified cells of (B) B/monocyte cell origin (CD74+), and (C) activated B cells and granuloma area (CD80+). Representative sections of xenografts obtained at transplant generations 1 (D), 28 (E), and 57 (F) show a constant uniform morphological appearance over time. The tumor is composed of large transformed lymphoid cells with vesicular nuclei and prominent nucleoli. Scale bar in F corresponds to 100 µm for images in C, D, E, and F, as well as the higher magnification inset within image A, and 400 µm for images in A and B.
Figure 3.
Xenografted tumors were highly aggressive in the hamster, with evidence of widespread metastatic disease.
(A) and (B) show metastases in the hamster spleen and kidney, respectively, from a GW-532, generation-2, cheek pouch tumor. (C) and (D) show metastases in the hamster spleen and lung, respectively, from a GW-584, generation-3, cheek pouch tumor. Metastatic tumors show similar cytological appearance to the cheek pouch xenograft tumors. Scale bar in image D corresponds to 200 µm for all images.
Figure 4.
FISH of GW-532, early and late generations, and GW-584 late generation tumor cells was performed with the human (green) and golden hamster (red) pancentromeric probes to evaluate the co-existence of species-specific genomic material within these cells.
A human colon carcinoma (GW-39) grown in the hamster cheek pouch served as a positive control. Within the GW-532 and GW-584 tumor cells, the hamster (red) and human (green) probes are identified in most cells and co-localized to the same cells (photoshop composite). On the other hand, human and hamster chromosomes show distinct, cell-specific localization within the human colon carcinoma xenograft, with hamster stromal tissue, and human colon carcinoma cells identified. DAPI background staining was performed on all tissues to identify the nuclei. Scale bar in the lower right corner corresponds to 100 µm for all GW-532 and GW-584 images and 67 µm for all of the higher magnification insets. For the GW-39 images, the scale bar corresponds to 200 µm.
Table 1.
PCR detection of human genes in malignant hybrid xenografts and control tissues.
Figure 5.
PCR evaluation of GW-532 and GW-584 for the presence of CD20, CD74, and CD71 genes.
DNA was extracted from formalin-fixed, paraffin-embedded specimens to be used as templates for PCR amplification with primers, as described in Supporting Information Table S1. The individual panels demonstrate the presence or absence of each gene within several generations of xenografted tumors. For PCR of CD20, the lanes contained GW-532 primary tumor (1), and xenograft tumors from generations 25 (2), 39 (3), and 115 (4); GW-584 xenografted tumors from generations 1 (5), 20 (6), and 57 (7); and controls Raji human lymphoma (8), CHO (Chinese hamster ovary) (9), and primers alone (10). Size markers are shown in lane M. Lanes are identical for PCR of CD74. For PCR of CD71, the lanes contained GW-532 xenografted tumors from generations 1 (1), 19 (2), 25 (3), and 115 (4); and GW-584 xenograft tumors from generations 1 (5), 20 (6), and 57 (7). Controls are identical to the CD20 and CD74 panels.